The present oinvention relates to systems for producing cigarettes in which the cigarettes are directly transferred from cigarette manufacturing machines to the cigarette batching hopper which feeds the cigarettes to the wrapping line of a packaging machine. The new system includes a store device for compensating for differentials in the output of said machines. More precisely, the subject matter of the invention is such a system which comprises a compensation store having a vertical-axis cylindrical body of high capacity.
As known, the cigarette producing systems or plants in use at present include two different kinds of machine, i.e.
1. Machines for producing cigarettes from minced and cured tobacco leaves, usually called cigarette manufacturing machines, and 2. Cigarette packaging machines. The machines of this second kind usually comprise:
Machines for producing packets of cigarettes, usually called packeting machines;
Machines for producing packs of cigarette packets, usually called packing machines, and
Wrapping machines for wrapping both single packets of cigarettes, also called "cellophaning machines", and single packs of cigarettes, usually called "over-wrapping machines".
In such plants, the cellophaning machines are arranged between the packeting machines and the packing machines, whereas the over-wrapping machines are arranged downstream of or after the packing machines.
It is also known that various kinds of cigarette manufacturing machine are adopted in practice and operate at a respective output speed of 2000 to 4000 cigarettes per minute.
There also exist various kinds of packaging machines which operate at output speeds of 100 to 120 up to 400 packets of cigarettes per minute, whereas the output speed of the packing machines is a function of the number of packets in each single pack. Among the wrapping machines for wrapping single packets of cigarettes, the Applicant's assignees' cellophaning machine which can wrap 400 packets of cigarettes per minute is widely used.
Single packs are usually wrapped by means of over-wrapping machines which operate at the same output speed as that of the packing machines co-operating therewith.
When considering the output speed of the various types of machine in use at present, it is found that depending on the types of machine used in forming the system or plant, a packeting machine can absorb the production or output of one to three manufacturing machines, whereas a cellophaning machine can deal with the output of one to three packeting machines.
As known, cigarettes are transferred from the manufacturing machine(s) to the packeting machine substantially in two different ways, i.e.
a. either by unloading the cigarettes into containers at the outlet of the cigarette manufacturing machine(s), the containers being then transferred and unloaded into the grouping or assembling hopper arranged to feed the packeting line of the packeting machine,
b. or by directly connecting such outlet of the cigarette manufacturing machine(s) to the assembling hopper arranged to feed the packeting line of the packeting machine.
The present invention concerns the latter branch of the art, in which the output of the manufacturing machine(s) is directly connected to the hopper of the packeting machine.
For such a kind of system, it was already suggested to feed cigarettes to the packeting machine by continuously transferring cigarettes from the cigarette manufacturing machine(s), the cigarettes, while being transferred, are arranged, as known, in a succession of single cigarettes or are gathered into batches by providing along the cigarette path means arranged to permit changes in the feeding speed to be made as a function of changes in the feeding capacity of the manufacturing machine(s) and in the receiving capacity of the packeting machine in such a way as to compensate for frequently occurring unbalances in the production or output of said machines.
According to the proposals known at present, said means arranged to permit variations in the cigarette flow rate to be made as a function of variations in the output and receiving capacities of said machines are provided, conceived and designed as having structures such as to be able to act on batches of cigarettes, in contact with each other inside or outside the hopper of the packeting machine.
On such batchwise treating of cigarettes in contact with each other either while the cigarettes are simply transferred or especially while the same are piled up in order to compensate for frequently occurring unbalances in the output of the power-consuming machines, the cigarettes are subjected to stress. The results, already during this initial step of the process, in a damage being caused to the cigarettes, in particular to the structural characteristics of the cigarettes (loss of compactness in the tobacco inside the cigarette envelope or paper).
For such reasons, systems have been proposed for the direct feeding system mentioned at paragraph (b), in which various transfer means and even means arranged to permit changes in the flow rate act on single cigarettes rather than on cigarette batches. In order to eliminate the drawbacks due to direct connection between machines running at different operating speeds, such systems have used a compensation store for compensating for unbalances which may occur owing to such different operating speeds, the cigarettes being stored one-by-one in the store and being withdrawn therefrom still one-by-one in case of need.
For instance, a device having a substantially cylindrical body which is about equal in height to the length of a cigarette, and comprising radial compartments all around it, the compartments being about equal in width to the diameter of a cigarette and variable in depth and being arranged to contain cigarette piles extending parallel to the axis of said cylindrical body is already known.
Such a device is continuously rotated about its own axis and its compartments, the depth of which uniformely increases or decreases depending on whether a storing or a withdrawal operation is being performed, successively reach a well determined position, so that during each 360.degree. rotation every compartment receives a cigarette in the first operating condition thereof and delivers it in the second condition.
It should be noted that in view of this such storing and withdrawing operations are carried out by following a spiral-like course.
From the above, it should appear that the maximum amount of cigarettes which can be stored is proportional to the diameter of the cylindrical body and this means that precise limits exist for the capacity and thus for the utility of such device.
Such a compensation store is subject to both size and weight limitations, the weight limitations being due to the fact that the speed of rotation of a particular storing and withdrawing mechanism has necessarily to match with the high output speed of the machines co-operating therewith.
it should be also noted that the cigarettes located in the innermost turns of said spiral will be only seldom withdrawn and this might be deleterious to the structural characteristics thereof.